The present invention relates to a device for injecting a fixing agent for anchoring a fastening element in a drilled hole. Devices of the foregoing type comprise a container which contains one component of the fixing agent and can be sealed, and an injection nozzle combined with a plunger which can be moved into the container.
Such a device has been disclosed in applicant's allowed patent application Ser. No. 668,077 now U.S. Pat. No. 4,609,129.
In the disclosed device, the injection nozzle is arranged on the plunger, and the total length of the plunger and the injection nozzle corresponds at least to the depth of the inner space in the container.
The second component of the fixing agent is accommodated in a cap-shaped cavity of the plunger. Water must be poured into the cavity before operation.
A holding force of conventional fastening elements is constituted on an expansible portion of the fastening element wedged in the drilled hole, for example by screwing of a fastening screw. As a result of expansion, however, stresses are produced, which allow only low holding forces, especially in porous and soft masonry. Fastening elements that can be anchored in a stress-free manner by the injection of a fixing agent around them have proved especially suitable for such materials. In a known anchoring process of this type, the fixing agent, for example a cement mixture, after being preliminarily mixed is poured into an injection device and by means of this device is then injected into the drilled hole. For a single mounting operation, however, the provision of such an injection device is generally not worthwhile. Furthermore, a further vessel is required for the preparatory mixing of the fixing agent. Both the injection device and this further vessel must be cleaned immediately after use or, in the case of a series of mounting operations, at short, regular intervals, to prevent the apparatus from becoming clogged and thus unusable.
DE-OS No. 27 30 110 discloses a container for once-only use. However, this container is still very expensive to manufacture. Handling this container also presents problems since a rod-shaped accessory element is necessary to press in the piston. DE-OS No. 33 41 283 discloses a container for once-only use, with which it is possible to inject the fixing agent, which is prepared by mixing inside the container, without the use of additional accessories. The container contains only one component, however, whereas the other component, which in the case of a cement mixture will be water, must be added using the plunger which is a beaker-like construction.